1. Field of the Invention
The present invention relates to a method for applying an image using a UV curable phase change ink and an ink jet printer suitable for performing such a method. In particular, the present invention relates to a method for applying an image comprising two curing steps, i.e. a pre-cure step and a post-cure step, wherein the two curing steps are performed using a first beam of UV radiation and a second beam of UV radiation, respectively.
2. Description of Background Art
Methods for applying an image onto a recording medium using a UV curable ink are known in the art. Generally, such methods comprise the step of applying the UV curable ink onto a recording medium, e.g. by jetting droplets of the ink using an ink jet printer.
After the ink has been applied onto the receiving medium, the ink is hardened by irradiating the ink with a suitable source of radiation, preferably UV radiation. It is known in the art that, when the layer of UV curable ink applied onto the receiving medium is relatively thick, it may not be possible to suitably cure the UV curable ink in one step. For example, the part of the ink layer close to the receiving medium may not completely cure. This problem may be addressed by curing the ink in a two-step procedure, as is explained for example in U.S. Application Publication No. 2008/0174648. Hence, it is known that applying UV radiation to a UV curable ink is required to suitably cure the ink.
However, irradiating a layer of ink applied onto a receiving medium using one or more sources of radiation may cause unwanted side-effects, for example in the case where UV curable phase change inks are used in the printing process. UV curable phase change inks may be fluid at elevated temperature and may be solid or semi-solid at lower temperatures. This type of ink may be jetted as a fluid at elevated temperate and may cool down after it has been applied onto the receiving medium, thereby transforming into a solid or semi-solid. When the temperature of UV curable phase change ink applied onto the receiving medium increases too much, the ink on the receiving medium may (partially) fluidize. This may cause print artifacts. For example, the gloss level of the resulting print after curing may be negatively influenced. In addition, coalescence of the ink may occur if the ink fluidizes before it is sufficiently cured. Hence, it may be difficult to cure a layer of UV curable phase change ink such that the ink is completely cured without obtaining print artifacts.
Therefore a need exists for applying an image using an UV curable phase change ink that mitigates the above mentioned problems.